Test tubes that accommodate samples of blood and the like are each made of glass or a resin. The samples accommodated in these test tubes are commonly mounted on vertically retainable test tube racks and test tube holders and conveyed using conveyance belt lines.
In addition, diverse holders and racks have heretofore been devised for retaining test tubes of different sizes and lengths.
To convey these diverse test tube racks and test tube holders, it has been necessary to change the widths and shapes of existing conveyance lines according to the shapes and sizes of the test tube racks and holders to be conveyed, and build new conveying lines.
A known, dedicated conveying system for test tube holders is described in Patent Document 1.